Filters are often used to remove solid particles such as e.g. dust, pollen, mold, or sand from an air or gas flow. Especially in applications where air quality is important, filters are often indispensible for the provision of clean air. As an example, gas turbines are generally operated with one or more filters such that particles are hindered to enter the turbine, thereby increasing the service life of the machinery. Furthermore, other applications and environments such as clean rooms, building ventilation systems, vacuum cleaners, engines, and so on, are often dependent on the supply of clean air by means of filters.
Many filters are characterized by that they have one or more filtering layers, made of paper or other similar fabrics, that are pleated shaped. By the pleats, the filter increases its effective area such that a more efficient filtering is provided, the air penetrating the filter from an upstream side to a downstream side of the filter medium.
For the support of a pleated filter medium, or any similar filter of its kind, a frame structure may be provided around the filter. A frame structure may offer a more stable construction for the filter such that the filter may better withstand deformations occurring from e.g. mechanical strain and/or air pressures through the filter during operation. Furthermore, frame structures often simplify filter mounting procedures, e.g. mounting of filters in air channels. The frames may provide a support for the filters in the mounting procedure and hinder filter deformations and damages at the filter edges. Moreover, the frame structures may be formed to provide an improved fit in the air channels, further facilitating the mounting of the filters.
The support of a filter by means of a frame structure applied to the filter edge is a solution frequently used in filter manufacturing. However, the frame structures often cannot provide an adequate sealing of the filters at the filter edges. As a consequence, this may lead to unwanted filter leakage at the edges, whereby the filter performance is deteriorated.